[Bug bootstrap/61078] [4.10 Regression] ESA mode bootstrap failure since r209897

[jgreenhalgh at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61078

--- Comment #1 from jgreenhalgh at gcc dot gnu.org ---
I'm happy to take a look at this, but I have no access to an s390 ESA mode
environment, so will struggle to make much progress.

If it is the case that s390 relies on PUSH_ARGS_REVERSED == 0, then r209897
will need to be reverted as it is clearly erroneous.

Otherwise, any reduced testcase you can find where we do the wrong thing
preparing stack arguments will be of great help hunting the bug.